It is known that one may color polyester compositions using copolymerized anthraquinone colorants at low levels (see, for example, U.S. Pat. Nos. 4,276,306; 4,359,570; and 4,403,092). The anthraquinone colorants have the inherent disadvantages, however, of having low extinction coefficients and being expensive to manufacture, although they have excellent thermal stability and fastness to light.
Thermally stable yellow methine colorants derived, for example, from alkyl cyanoacetates and malononitrile active methylene components have also been used to produce polyester compositions containing copolymerized colorants therein and having excellent nonextractability of the colorants and good lightfastness (see U.S. Pat. No. 4,617,373). These yellow methine colorants have the advantage of having high extinction coefficients and thus provide excellent color yield. This reference also discloses red methine colorants which are derived from 3-cyano-4-phenyl-2-(5H)-furanone as the active methylene component (e.g. Example 761). These red compounds, however, are highly fluorescent and have inadequate lightfastness to produce satisfactory colored polyester packaging compositions where substantial exposure to sunlight is involved.
High tinctorial red colorants containing a tricyanovinyl group as part of the chromophoric system are also known and are reported to be useful for dyeing polyester fibers in lightfast red shades (U.S. Pat. No. 2,762,810). An example of this type of compound is as follows: ##STR1##
Although this type of structure generally provides bathochromic colors (red) versus the corresponding yellow dicyanovinyl compounds and have high extinction coefficients, they have poor thermal stability and are completely destroyed under high temperature polyester forming conditions.
It is also noted that bathochromic (red) methine compounds have been prepared from 7-substitutedamino-coumarin-3-aldehydes and active methylene compounds such as malononitrile (U.S. Pat. No. 4,018,796). An example is as follows: ##STR2##
These compounds also have high extinction coefficients, but are highly fluorescent and exhibit poor thermal stability under polyester reaction conditions.
Also, U.S. Pat. No. 4,373,102 describes somewhat structurally related isoindoline compounds containing substituted ethylenic chromophoric groups which are reported to give red to blue shades when dyed on polyester fibers. A typical example is as follows: ##STR3##
The isoindolines, however, generally have inadequate thermal stability when tested as colorants for copolymerization into polyesters.
Furthermore, structurally related to the compounds of this invention are 5-dicyanomethylene-2-oxo-3-pyrroline compounds described in U.S. Pat. No. 3,096,339 which give yellow to blue shades When dyed on polyester fibers. A typical dye is as follows: ##STR4## These compounds have high extinction coefficients, but have shown poor thermal stability at the high temperatures required for polyester manufacture.
Finally, it is known that certain compounds which contain a negatively substituted 2,5-dioxopyrrolin-3-yl moiety are useful as bathochromic red dyes for dyeing synthetic fibers. A typical colorant is as follows: ##STR5##
These compounds can be prepared by reacting an active hydrogen compound (A-H) with 2-chloro-3-negatively substituted maleimides: ##STR6##
There is no teaching, however, in this patent that would lead one to believe that the compounds of this invention would have the required excellent thermal stability to allow them to be copolymerizable under polyester manufacturing conditions to produce colored polyesters.